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991.
992.
Takezawa Y Tanaka K Yori M Tashiro S Shiro M Shionoya M 《The Journal of organic chemistry》2008,73(16):6092-6098
Metal-mediated base pairing with artificial ligand-bearing nucleosides allows site-selective metal incorporation inside DNA duplexes. In particular, this strategy has provided a general way of discrete, heterogeneous metal arrays in a programmable manner. To increase the kind of metallo-building blocks, we have newly synthesized two artificial nucleosides which have an O, S-donor ligand as the nucleobase moiety, mercaptopyridone ( M) and hydroxypyridinethione ( S). These nucleosides were found to efficiently form metal-mediated base pairs with soft transition metal ions such as Pd (2+) and Pt (2+). 相似文献
993.
The diastereoselective construction of stereotriads having consecutive methyl, hydroxy, and methyl substituents was realized by the substrate-controlled crotylation of beta-branched alpha-methylaldehydes with potassium crotyltrifluoroborates. Especially, crotylation of 2-(1,3-dithian-2-yl)propanal with potassium ( E)-crotyltrifluoroborate afforded, in good yield and with excellent diastereoselectivity, a useful building block that has different and potential functional groups on both ends. 相似文献
994.
Antônio Gomes dos Santos Neto Franciele de Matos Morawski Ana Caroline Ferreira Santos Cláudia Quintino da Rocha Roberto Batista de Lima Marília Oliveira Fonseca Goulart Clenilton Costa dos Santos Flávio Colmati Antônio Euzébio Goulart Santana Marco Aurélio Suller Garcia Auro Atsushi Tanaka 《Electroanalysis》2023,35(5):e202200390
Here, we report multiwalled carbon nanotubes (MWCNTs) functionalized with γ-cyclodextrins (γCD) as a novel electrochemical strategy for Rutin determination, showing superior performance than β-cyclodextrins (βCD) modified MWCNTs, suggesting an adequate environment for host-guest interactions. Under optimized conditions, the sensor showed a linear range of 39–975 nmol L−1 and a limit of detection of 7 nmol L−1. When tested with quercetin, catechin, and caffeine, the platform presented high selectivity with an interference response <10 %. The method was employed to quantify Rutin in spiked pharmaceutical and herbal extracts, providing recovery of 93–98.4 %. Also, HPLC-PDA confirmed the method‘s accuracy. 相似文献
995.
Dr. Yoshinobu Kamakura Dr. Chomponoot Suppaso Issei Yamamoto Ryusuke Mizuochi Yusuke Asai Prof. Dr. Teruki Motohashi Prof. Dr. Daisuke Tanaka Prof. Dr. Kazuhiko Maeda 《Angewandte Chemie (International ed. in English)》2023,62(28):e202305923
Certain metal complexes are known as high-performance CO2 reduction photocatalysts driven by visible light. However, most of them rely on rare, precious metals as principal components, and integrating the functions of light absorption and catalysis into a single molecular unit based on abundant metals remains a challenge. Metal-organic frameworks (MOFs), which can be regarded as intermediate compounds between molecules and inorganic solids, are potential platforms for the construction of a simple photocatalytic system composed only of Earth-abundant nontoxic elements. In this work, we report that a tin-based MOF enables the conversion of CO2 into formic acid with a record high apparent quantum yield (9.8 % at 400 nm) and >99 % selectivity without the need for any additional photosensitizer or catalyst. This work highlights a new MOF with strong potential for photocatalytic CO2 reduction driven by solar energy. 相似文献
996.
Taichi Mitsumoto Dr. Yuya Ashida Dr. Kazuya Arashiba Dr. Shogo Kuriyama Akihito Egi Prof. Dr. Hiromasa Tanaka Prof. Dr. Kazunari Yoshizawa Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2023,62(43):e202306631
We newly designed and prepared a novel molybdenum complex bearing a 4-[3,5-bis(trifluoromethyl)phenyl]pyridine-based PNP-type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum-imide complexes bearing various substituted pyridine-based PNP-type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification. 相似文献
997.
Makiko Tanaka Kazusa Yukimoto Kei Ohkubo Shunichi Fukuzumi 《Journal of photochemistry and photobiology. A, Chemistry》2008,197(2-3):206-212
Photoirradiation of various 10-methylacridinium ions (AcrR+, R = H, iPr, and Ph) intercalated in DNA results in ultrafast intramolecular electron transfer, followed by rapid back electron transfer between AcrR+ and nucleotides in DNA. The electron-transfer dynamics in DNA were monitored by femtosecond time-resolved transient absorption spectroscopy. Both acridinyl radical and nucleotide radical cations, formed in the photoinduced electron transfer in DNA, were successfully detected in an aqueous solution. These transient absorption spectra were assigned by the comparison with those of DNA nucleotide radical cations, which were obtained by the intermolecular electron-transfer oxidation of nucleotides with the electron-transfer state of 9-mesityl-10-methylacridinium ion (Acr–Mes+) produced upon photoexcitation of Acr+–Mes. Photoinduced cleavage of DNA with various acridinium ions (AcrR+, R = H, iPr, Ph, and Mes) has also been examined by agarose gel electrophoresis, which indicates that the rapid intramolecular back electron transfer between acridinyl radical and nucleotide radical cation in DNA suppresses the DNA cleavage as compared with the intermolecular electron-transfer oxidation of nucleotides with Acr–Mes+. 相似文献
998.
Tanaka A Matsuo Y Hashimoto Y Ijiro K 《Chemical communications (Cambridge, England)》2008,(36):4270-4272
Platinum metal was sequence-specifically deposited on the DNA block copolymer synthesized by the Klenow fragment of E. coli DNA polymerase I (3'-5' exonuclease deficient). 相似文献
999.
Inukai J Miyatake K Ishigami Y Watanabe M Hyakutake T Nishide H Nagumo Y Watanabe M Tanaka A 《Chemical communications (Cambridge, England)》2008,(15):1750-1752
A luminescent porphyrin dye film has been coated onto a transparent separator on the cathode side of a direct methanol fuel cell (DMFC) to visualise clearly oxygen distribution under operating conditions by analysing emission from the dye. 相似文献
1000.
Nakamura S Kobayashi L Tanaka R Isoda-Yamashita T Motomura K Moroi Y 《Langmuir : the ACS journal of surfaces and colloids》2008,24(1):15-18
Solubilization of benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, n-pentylbenzene, and n-hexylbenzene into micelles of decanoyl-N-methylglucamide (Mega-10) was studied, where equilibrium concentrations of the above solubilizates were determined spectrophotometrically at 303.2 K. The concentration of the above solubilizates remained constant below the critical micelle concentration (cmc) and increased linearly with an increase in Mega-10 concentration above the cmc. The Gibbs free energy change of the solubilizates from the aqueous bulk to the liquid solubilizate phase was evaluated from the dependence of their aqueous solubility on the alkyl chain length of the solubilizates, which leads to -3.46 kJ mol-1 for DeltaG(0)(CH), the energy change per CH2 group of the alkyl chain. The first stepwise solubilization constant (K(overline)1 ) was evaluated from the slope of the change of solubilizate concentration versus Mega-10 concentration. The Gibbs free energy change (DeltaG(0,s)) for the solubilization decreased linearly with the carbon number of the alkyl chain of the solubilizates, from which DeltaG(0,s)(CH2) as evaluated to be -2.71 kJ mol-1. The similar values above clearly indicate that the location of the alkyl chain is a hydrophobic micellar core, which is also supported by the absorption spectrum of the solubilized molecules. 相似文献